Drive mechanism for a steerable propeller



y 12, 1970 J BECKER 3,511,209

DRIVE MECHANISM FOR A STEERABLE PROPELLER Filed June 18, 1968 3 Sheets-Sheet 1 In van t or: a055, Eff/([6 May 12, 1970 J. BECKER 3,511,209

DRIVE MECHANISM FOR A STEERABLE PROPELLER Filed June 18, 1968 3 Sheets-Sheet 2 In ventor M0567: EEC/(5E Z/MZW 5M 17% May 12, 1970 JQIBEICKER 3,511,209

DRIVE MECHANISM FOR A STEERABLE PROPELLER Filed June l8 1968 3 Sheets -Sheet 5 Fig. 3

United States Patent 3,511,209 DRIVE MECHANISM FOR A STEERABLE PROPELLER Josef Becker, Oberspay (Rhine), Germany, assignor to Schottel-Werft, Josef Becker K.G., Oberspay (Rhine), Germany, a corporation of Germany Filed June 18, 1968, Ser. No. 738,038 Claims priority, application Germany, Nov. 10, 1967 Sch 41,547 Int. Cl. B6311 1/14, 5/06 U.S. Cl. 11535 7 Claims ABSTRACT OF THE DISCLOSURE A drive mechanism for a steerable propeller on a watercraft wherein the propeller is driven by a drive motor through speed reduction gearing beneath the water level and in which the propeller is steerable about a vertical axis, said speed reduction gearing being located in a housing below the water line and having a speed reduction greater than that in the above-water portion of the housing.

This invention relates to a drive mechanism for a steerable propeller on a watercraft or the like in which the propeller is driven by a drive motor through speed reduction gearing beneath the water level and in which the propeller, for the purpose of steering the vehicle, is pivotable about a vertical axis.

Steerable propellers which are pivotable about a vertical axis for the purpose of steering are driven through a vertical shaft leading underneath the water level and tend, due to the torque, to rotate'about said vertical axis. To prevent such rotation, a support fin is generally provided which, since it is positioned against the water stream at all times, consumes power.

The gear train between the drive motor and the propeller is basically of a Z-shaped structure, namely a drive transfer mechanism with an essentially horizontal main axis driven by the motor. The power output of the motor is conducted to a vertical shaft by a bevel gear or the like,said shaft extending underneath the water level, and from there the drive is conducted to a horizontal propeller shaft by means of a bevel gear or the like. The effectiveness of the steerable propeller depends among others on the relation of the diameter of the propeller to the diameter of the gear housing which contains the drive train positioned underneath the water. The size of the latter depends on the size of the gears of the gear train and these in turn depend on the torque to be transmitted. The torque transmitted by the vertical shaft produces a moment of rotation which affects the control drive.

The basic purpose of the invention is to decrease the resistance to flow of the portion of the steerable propeller which is positioned underneath the water and to improve the effectiveness thereof, same being determined by the cooperation between propeller and underwater housing. Furthermore, the moment acting on the control drive is to be reduced.

To attain said basic purpose the invention provides that the underwater portion of the gear train has greater speed reduction gearing than the above-water portion. By means of the invention, the number of rotations of the shaft leading underneath the water line is increased and thus the torque transmitted by same is decreased which results in the support moment produced by the fin being smaller. Furthermore, the number of rotations of the gear driven by the vertical shaft leading underneath the water level is smaller so that the corresponding underwater housing can be smaller. Both facts reduce the Hce resistance of the underwater portion of the steerable propeller.

The effectiveness of the invention is further increased in such a way that the entire reduction of speed is formed in the underwater portion of the gear train or in such a way that the above-water portion of the gear train provides an increase in speed and the underwater portion provides a reduction in speed.

In order to be able to construct a small underwater housing, the invention further provides that the underwater portion of the gear train has more than one pair of gears. Extremely small wake is obtained by an embodiment of the invention wherein the underwater portion of the gear unit is at least partially a planetary gear. Optimum dimensions are achieved if the underwater portion of the gear unit is composed of a bevel gear and a spur gear type of planetary gear system.

Thus, the underwater portion of a steerable propeller has such a structure that the housing containing the underwater portion of the gear train has a diameter which is less than one-third of the diameter of the propeller. Utilizing the principles of the invention consistently, the underwater portion of the invention is characterized in that the housing containing the underwater portion of the gear train has a diameter which is approximately onefourth or less of the diameter of the propeller.

A particular advantage of the invention is that a multistage step-down gearing is provided in the housing carrying the propeller since with a pure Z-drive in the steerable propeller, namely in a gear train with two horizontal shafts and a vertical shaft about the axis of which or approximately about the axis of which the underwater portion is pivoted for the purpose of steering, the pivot axis can obtain a high number of rotations and a small torque. It is particularly advantageous to construct the invention with a planetary gear system because with same a very high reduction of speed can be put in a small area.

Further characteristics and advantages of the invention can be understood by reading the following description.

The invention is described and illustrated by one embodiment in the drawings, in which:

FIG. 1 is a side elevational view of the entire structure of a steerable propeller.

FIG. 2 schematically illustrates a side view of a gear train embodying the invention.

FIG. 3 is a partially sectioned, side elevational view of the gear train of FIG. 2.

A steerable propeller, as this is known, is used to drive and to steer watercrafts. For this purpose, said propeller is mounted to the outer side of the boat 10 at a suitable place, for example the stern, in a suitable manner. The fastening means can be of any conventional variety and, therefore, are not illustrated. The water line is identified by the reference W in FIG. 1.

The drive is caused by a drive motor, not illustrated, through a conventional torque transfer mechanism (not illustrated) and drive shaft 11 to a coupling flange 12 secured to one end of a horizontal drive shaft 14 which is supported in the above-water housing 13. A bevel gear 15 is mounted to the other end of the drive shaft 14, said bevel gear being in meshing engagement with a bevel gear 16 secured to a vertically arranged center shaft 17, said center shaft 17 extending from the above-water housing 13 through a control housing 18, a shaft housing 19 and terminating in an underwater housing 20. The center shaft 17 can, if desired, be made of one piece. However, it is recognized that the shaft 17 can, for reasons of installation, be composed of several pieces, for example, 17a and 17b connected together a coupling 21. A bevel gear 22 is secured to the lower end of the center shaft 17 and is rotatable with the part 17a of the center shaft 17. The bevel gear 22 is in meshing engagement with a bevel gear 23. The bevel gears 22 and 23 form a drive for the propeller 24 which is secured to one end of a horizontally positioned propeller shaft 24a in a known manner.

The portion of the underwater housing which contains said drive will be referred to hereinafter as a pear 25 because of its shape. The propeller shaft 24a is rotatably supported coaxially Within the pear by the bearings 26 to 28. The bevel gear 23 is secured to a sleeve 29 which telescopes the propeller shaft 24a and is supported by the bearings 30 and 31 in the pear. A sun gear 32 of a planetary gear system is loosely supported by means of an intern-a1 gearing on the sleeve 29 or an extension thereof at the opposite end thereof from the propeller. A shaft 33 is provided for the sun gear 32 and has for the mentioned purpose external gearing engaging the internal gearing on the sleeve 29. The internal and external gearing are identified by the reference 34. The sun gear 32 is fioatingly guided by the gearing composed of a number of planetary gears 35, one of which is illustrated in FIG. 3 and two of which are illustrated in FIG. 2. The planetary gears are arranged, in a known manner, in a planetary carrier 36. The planetary carrier is, in a known manner, secured to th propeller shaft 24a, by coupling gearing 37, for exampie. The planetary gears 35 are in meshing engagement with the gearing of a ring gear 38 which is secured to the pear 25. The bearings 27 and 28 on the end of the propeller shaft 24a adjacent the planetary gear carrier 36 permit a radial displacement of said shaft so that the planetary gears 35 along with the planetary carrier 36, the propeller shaft 24a and the sun gear 32 are guided by the ring gear 38, whereby an equal load is obtained on all of the teeth in meshing engagement.

The remaining bearings in the above-described gear train do not provide any special results and, therefore, need not be described. They are schematically illustrated as ball bearings in FIG. 2 and as roller and tapered roller hearings in FIG. 3. Sliding bearings can also be utilized if the situation requires it.

The underwater housing 20 is secured to a control sleeve 39 which is supported by suitable bearings 40 and 41 in the shaft housing 19 (FIG. 2). The shaft housing 19 and control sleeve 39 are sealed by means of a commonly known sealant 42. The upper end of the control sleeve 39 has a plate-like bevel gear 43 secured thereto and is in meshing engagement with a bevel gear 44 fixed to one end of a control shaft 45 and rotatable therewith. A worm gear 46 is secured to the other end of the control shaft, said worm gear being engaged by a worm 47 which is supported in a known manner. The mentioned parts 43, 44, 46 are arranged in the above-mentioned control housing 18. The worm has a stub shaft 48, said stub shaft having a slot 49 or any equivalent element enabling a connection between the stub shaft and a control drive shaft 50 connected to the steering wheel of the boat (not illus trated). It is also possible to connect an electric, hydraulic of pneumatic motor for a long-range transmission to said stub shaft 48. The drive for the control shaft is schematically indicated by an arrow 53 in FIGS. 2 and 3.

The function of such a steerable propeller is known and, as such, does not require a discussion so that the desired effect needs only to be described. If a torque is fed to the drive shaft 14 (arrow 51), said torque will be transferred through the gear elements 15, 16, 17, 22, 23 to the underwater portion 52 of the gear train provided in the pear 25. Since the pear 25 is rotatably supported in the shaft housing 19 together with the underwater housing 20 and the control sleeve 39, the center shaft 17 not only transmits a torque to the propeller through the underwater portion of the gear train but also transmits a reaction moment to the housing parts 25, 28 and 39 which are urged to rotate in an opposite direction relative to the center shaft 17. The reaction moment is eliminated by the control drive 43, 44, 46, 47 and by the fin 54. The reaction moment being partially eliminated by the control drive is undesirable since this puts a load on the control drive system and the corresponding gear parts. The partial elimination of the reaction moment by the fin 54 is undesired because the fin is dependent on the stream of water therepast and would thus decrease the effectiveness of the steerable propeller. In some cases, very large steerable propellers might not be provided with any fins so that the control gear unit must take up the entire reaction moment.

According to the invention, the above-water portion 55 (FIG. 3) of the gear train, namely that portion of the gear train which is arranged in the housing parts which are stationary relative to the boat, has no step-down gearing or even speed-up gearing therein. Thus, the center shaft rotates at a high speed, for example, at a number of rotations equal to the drive motor or even faster. This results in a torque which is correspondingly small on the center shaft 17 and also a small reaction moment. The main portion of the step-down gearing, preferably the entire step-down gearing or even more than the step-down gearing from the rnotor to the propeller (since transmission takes place in the above-water part), is placed in the underwater portion 52 of the gear unit. In order to put said step-down gearing in the pear, same is divided into several steps, namely divided into several pairs of gears. The novel feature of the invention is to produce the stepdown gearing effect with a planetary gear system, since a spur-gear planetary gear system is particularly advantageous because spur gears can be worked better, run smother and are relatively more durable than bevel gears.

Through the use of, or the combination with a planetary gear system, the pear" can have a small diameter in relationship to the propeller. It is, therefore, a particular characteristic of the invention that the diameter of the pear be only one third and less of the diameter of the propeller. Using the principles of the invention consistently, the diameter of the pear can even be only one-fourth of the diameter of the propeller.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A drive mechanism for a propeller positioned below the water line on watercraft and the like, said propeller being driven by an engine inboard of the watercraft and controllable about a generally vertical axis of a steering shaft, comprising:

frame means;

a drive shaft rotatably supported by said frame means, said drive shaft being substantially parallel to said steering shaft and having a first gear secured to the lower end thereof and rotatable therewith;

enclosure means below said water line of said watercraft secured to the lower end of said steering shaft and rotatable therewith, said lower end of said drive shaft extending into said enclosure means;

a generally horizontal driven shaft rotatably supported in said enclosure means and having said propeller secured to one end thereof externally of said enclosure means and rotatable therewith; and

planetary gear means in said enclosure means coupling said first gear on said drive shaft to said driven shaft for effecting a high-ratio reduction of speed from said drive shaft to said driven shaft while maintaining minimal diameter of said enclosure means, said dialmeter being taken radially to said driven shaft, an

steering means operatively connected solely to said steering shaft, and drive input means operatively connected solely to said drive shaft, whereby said drive shaft is completely independent of said steering shaft thereby to prevent torque from said drive mput means from influencing said steering means other than through said drive shaft.

2. The drive mechanism defined in claim 1, including means for effecting a high-speed rotation of said drive shaft and said first gear to reduce the torque output thereof, said planetary gear means effecting a gear reduction to provide the desired rotational speed for said driven shaft and said propeller.

3. The drive mechanism defined in claim 2, wherein said planetary gear means includes a ring gear fixed to said enclosure means a planetary carrier having a plurality of planet gears thereon fixed to said driven shaft and rotatable therewith and a sun gear coupled to said first gear and driven thereby to effect a reduction in the speed of rotation of said driven shaft relative to said drive shaft and said first gear and to minimize the torque transmittable to said steering shaft.

4. The drive mechanism defined in claim 1, wherein said enclosure means housing said planetary gear means is less than one-third the diameter of said propeller.

5. The drive mechanism defined in claim 1, wherein said enclosure means housing said planetary gear means is less than one-fourth the diameter of said propeller.

6. A drive mechanism for a propeller positioned below the water line on watercraft and the like, said propeller being controllable about a generally vertical axis of a steering shaft, comprising:

frame means;

drive means;

a drive shaft rotatably supported by said frame means, said drive shaft being parallel to said steering shaft and having a first gear secured to the lower end thereof and rotatable therewith;

speed step-up means operatively between said drive means and said drive shaft for effecting a high-speed rotation of said drive shaft to reduce the reaction torque thereof;

10 said driven shaft in said enclosure means for reducing the speed of said driven shaft while minimizing the diameter of said enclosure means in a direction radial of said driven shaft.

7. The device defined in claim 6, wherein said gear reduction means comprises planetary gearing within said enclosure means, means driving the sun gear of said planetary gearing from said drive shaft and means connecting the planet carrier of said planetary gearing to said driven shaft, whereby a high ratio of gear reduction between the drive shaft and the driven shaft is obtained while minimizing the dimension of said enclosure means in a direction radial to said driven shaft.

References Cited UNITED STATES PATENTS 1,389,622 9/1921 Buehler 74797 FOREIGN PATENTS 1,234,308 5/1960 France.

983,462 2/1965 Great Britain.

TRYGVE M. BLIX, Primary Examiner 

